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BQ25798EVM: IC’s temperature rise by approximately 20 degrees

Ernest Yong
Expert 4600 points
Part Number: BQ25798EVM

Hi Team,

My customer is facing issue with the battery charger BQ25798EVM eval kit.

When they connect an external USB charger it draws ~200mA with no load or battery connected to VSYS.

The IC’s temperature appears to rise by approximately 20 degrees.

They also connected an external power supply to TP23 (VBUS) and it was also drawing ~200mA @5V with no load or battery attached.

 

Can you please let me know if there is anything they can try or should they attempt to replace the IC on the eval board?

  • 0
    TI__Guru**** 167196 points

    HI Ernest,

    Can you customer try connecting to a bench power supply instead of USB? Can your customer try implementing HiZ mode either by pulling ILIM_HIZ pin low or setting EN_HIZ bit =1?  If still current flow, then IC is damaged. Why are D+/D- pins at 2.6V?

    Regards,

    Jeff  

  • 0 in reply to Jeff F
    TI__Expert 4600 points

    Hi Jeff,

    Thank you. Sorry for the delay in response. Customer have connected the unit again to 5V bench power supply. JP21 has been connected to pull the ILIM_HiZ pin low. The power consumption from the power supply has been reduced to ~4mA and the IC does not over heat or make an audible noise .

    Please the screen shot below with the measurements.

    ADC (D+) is no longer 2.6V it is 0V.

    When customer change back the jumper from JP21 to either JP13 or JP14 the current consumption by the power supply returns to ~220mA see screenshot below. They are not sure why ADC VBATT reads 4.33V when there is no battery present.

  • 0 in reply to Ernest Yong
    TI__Guru**** 167196 points

    Hi Ernest,

    Can you screen shot the status and fault register page?  Keep in mind that the fault registers clear after being read so don't read twice.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    TI__Expert 4600 points

    Hi Jeff,

    Please see the screenshot below for the fault registers.

    It appears that VBAT_OVP_STATUS is active?

    Thanks!

  • 0 in reply to Ernest Yong
    TI__Guru**** 167196 points

    Hi Ernest,

    The fault flag means that there was a VBAT_OVP event in the past.  The charger is currently not in VBAT_OVP state.  Is the converter switching, i.e. if you put an oscope probe on SW1 or SW2, is there a squarish, pulsing waveform?  If not, then the IC is damaged.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    TI__Expert 4600 points

    Hi Jeff,

    Customer had captured some scope waveforms of the switching this morning please see the attached.

    It appears the IC is switching, no load on Vsys or battery were connected. The IC was drawing ~120mA from a power supplying 5V.

    Thank you so much for your constant help!

    Best regards,

    Ernest

  • 0 in reply to Ernest Yong
    TI__Guru**** 167196 points

    HI Ernest,

    That switching waveform is wrong.  Either the IC is damaged or the board was not soldered correctly.

    Regards,

    Jeff